Fluid operated percussion tool

ABSTRACT

Percussion tool actuated by an incompressible fluid, characterized in that the upper chamber of the cylinder is constantly responsive to the fluid pressure while the pressure is alternately applied to and removed from the lower chamber.

[ *June26,1973

United States Patent [191 ajouanine [56] References Cited UNITED STATES PATENTS Inventor: Remi F. Alajounnine, Clamart,

France I 1,591,930 7/1926 173/137 2,624,177 1/1953 Warren............................... 173/116 Forges et Atellers de Meudon, Soclete 2,359,733 11/1953 7 /1 37 Bassinger et e d S t u a H n o d u m e m y n 0 n A NC. e U Q S S A N 7 Seine), France Notice: The portion of the term of this Examiner-lames PP Attorney-Amster & Rothstein patent subsequent to Oct. 25, 1968 has been disclaimed.

Jan. 16, 1968 Appl. No.: 698,326

[22] Filed:

Percussion tool actuated by an incompressible fluid, characterized in that the upper chamber of the cylinder is constantly responsive to the fluid pressure while the pressure is alternately applied to and removed from the lower chamber.

2 Claims, 7 Drawing Figures FLUID-OPERATED PERCUSSION TOOL BACKGROUND OF THE INVENTION This invention relates to percussion tools of the type designed either for working metals by chipping or crushing, such as chipping-tools, riveting hammers and the like, or for disintegrating materials such as concrete, rocks, ores (breakers, hammers, road and concrete-breakers), or for drilling blast mine holes, ventilation holes, cable passages, or other tools (drill hammers).

The tools usually employed for these various types of works operate on compressed air and have been adopted everywhere on account of their light weight, sturdiness and handiness. However, they are objectionable on account of various inconveniences such as their high noise level caused by the air expansion, and also the relatively low efficiency of air motors.

To avoid these inconveniences many manufacturers have produced percussion tools actuated by an incompressible fluid, which comprise like air-powered tools a piston responsive to the fluid action and various means for distributing and accumulating this fluid in order to exert on the piston efforts directed in one or the other direction as necessary for reciprocating same, and to utilize this motion in one direction for applying to the tool proper a blow the energy of which is transmitted to the material to be worked upon.

SUMMARY OF THE INVENTION The percussion tool actuated by an incompressible fluid according to this invention, which comprises a piston slidably mounted in a cylinder and forming therein an upper chamber and a lower chamber adapted to be fed with incompressible fluid, and capable of transmitting in the form of successive blows the energy contained in the fluid under pressure, which piston is subjected to this end to a reciprocating motion sustained by a fluid distribution system, is characterized in that the upper chamber of the cylinder is constantly responsive to said fluid pressure while the pressure is alternately applied to and removed from said lower chamber.

This tool is characterized by advantageous features FIG. 2 is a similar view of the same apparatus during the return stroke of the piston;

FIG. 3 illustrates the apparatus of FIGS. 1 and 2 at the end of the return stroke of the piston;

FIG. 4 illustrates the apparatus during the positive stroke of the piston;

FIG. 5 is a diagrammatic view similar to the preceding Figures, showing a percussion and rotary tool of the drill type, during the return stroke of the piston;

FIG. 6 is a cross-section taken upon the line IV-IV of FIG. 5;

FIG. 7 is a cross-sectional view taken upon the line VlI-VII of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The tool illustrated in the various figures of the drawing comprises essentially a body 1, a piston 2, a fluid distributor 3, a monitoring slide valve 4, a fluid accumulator consisting of a cylinder 5, a piston 6 and a return spring 7, and a bit 8; the incompressible fluid, for example a suitable oil, is fed to the apparatus via an inlet port 9; the distributing system directs the supply of coil under pressure into the upper chamber 10 via a duct 11 and the lower chamber 12 is alternatively set under pressure and connected to the exhaust or return line 13 leading to the reservoir. The distributor valve 3 is constantly urged by a spring 14 to its uppermost position, and a port 15 is provided for returning the oil to the reservoir.

This apparatus operates as follows: As the piston anvil-block 2 has just struck the head of bit 8 as shown in such as low noise level and high power efficiency,

whereby the above-mentioned inconveniences are definitely removed, and furthermore its piston can be caused to travel at a very high speed during the impact and at a very low speed during the return stroke.

This percussion tool may be completed by providing means for rotating the drill bit or like chised or point, in order to constitute a drill hammer operating somewhat like an air drill.

Other features and advantages of this invention will appear as the following description proceeds with reference to the accompanying drawing illustrating diagrammatically by way of example two typical forms of embodiment of a fluid-actuated tool constructed according to the teachings of this invention.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic longitudinal section showing the mechanism of a percussion tool of the concretebreaker type, the parts being illustrated in their relative positions obtaining just when the piston anvil-block is striking the drill bit shank;

FIG. 1, the upper face of monitoring slide valve 4 is subjected to the pressure prevailing in chamber 10 and permits the subsequent flow of oil under pressure from the supply port 9 to the upper face of distributor 3. The latter is then moved to the position shown in FIG. 2;

1 under these conditions the oil under pressure is fed simultaneously to chambers 10 and 12 via ducts 11 and 13, respectively; the cross-sectional areas of chambers 10 and 12, designated by the reference letters s and S, respectively, are such that the oil pressure exerts a reduced effort on piston 2 in order to impart a relatively low return or upward speed thereto, thus avoiding the necessity of providing means for damping same at the end of its return stroke.

During this upward stroke of the piston (which requires but a very reduced oil output) the excess output from the supply pump is absorbed by the accumulator 5,6, 7 and subsequently delivered to provide in con- When the piston 2 has completed its return stroke as shown in FIG. 3, the pressure in chamber 12 is applied to the bottom face of monitoring slide valve 4 and the upper face of this valve communicates with the exhaust line to the reservoir. Under these conditions the monitoring slide valve 4 will remove the pressure from the top face of distributor 3 and the latter is returned by spring 14 to the position illustrated in FIG. 4.

The chamber 12 communicates with the exhaust line leading to the reservoir while the pressure is exerted only in chamber 10 and, by acting upon the piston cross-sectional area, it generates an effort imparting a high speed thereto during the positive stroke. The oil output during this phase of the tool operation is provided by the feed pump and completed by the accumulator.

At the end of the positive stroke or blow, the piston 2 resumes the position illustrated in FIG. 1 and the apparatus is thus read to perform the next cycle.

The percussion drill illustrated in FIGS. 5 to 7 of the drawing comprises essentially the same component elements as the concrete breaker illustrated in the preceding Figures, plus the elements necessary for rotating the bit, namely:

A tool holder 16 in the form of a socket provided with a hexagonal axial passage and an external integral toothed wheel, a hydraulic motor consisting of a pair of meshing gears 17 and 18 of which the former 17 carries a depending shaft provided at its lower end with another pinion 20, a pair of non-return valves 21,22 and an oil throttling orifice 23. The bit driving motor is fed via a duct 24 and the exhaust is via another duct 25 through said non-return valve 22.

This arrangement operates as follows:

During the return stroke of piston 2 the non-return valve 21 is closed and the throttling orifice 23 creates a pressure drop causing the pressure in duct 24 to rise to a value slightly higher than that prevailing in the other parts of the circuit. This pressure differential causes the gear motor 17,18 to rotate and this rotary motion is transmitted via shaft 19 and pinion 20 to drive the tool holder 16 and consequently the hexagon shank bit 8 engaging the correspondingly shaped axial passage of socket 16. The function of the throttling orifice 23 is to adjust the pressure loss and therefore the motor torque. During the operative stroke or blow of piston 2, valve 22 is closed and valve 21 is open. Thus, the gear motor 17,18 is not supplied and is therefore inoperative, the same also applying to the bit 8.

From the foregoing it is clear that the hydraulic percussion tool according to this invention operates exactly like an air-operated drill, the bit 8 revolving about its axis during the return stroke of piston 2 by a predetermined angle depending on the dimensional characteristics of the tool, such as cross-sectional areas s and S, piston stroke, diameter of throttling orifice 23, etc.. With this particular arrangement it is possible to use the same percussion bits and chisels as those used with compressed-air breakers and drills, and to take full advantage of the shapes of these chisels, bits and like steels specially designed for drilling hard rocks.

Of course, the specific forms of embodiment shown and described herein are given by way of example only and should not be construed as limiting the present invention since many modifications and variations may be brought thereto without departing from the spirit and scope of the invention as will readily occur to anybody conversant with the art, this remark applying for example to the hydraulic means utilized for actuating an anvil block piston of breakers, hammers and the like with a view to obtain a mode of operation similar to that of air-powered tools of the same character, and more particularly on the one hand a reduced piston return speed whereby the use of damping means operating at the end of the return stroke can be dispensed with, and on the other hand a system for rotating the bit about its axis which impart to the tool the same functional characteristics as those of an air-powered tool without resorting to the usual means such as pawls, ratchets, helical grooves or cam faces, rotary-driving bars, etc..

Thus, notably, the distributor 3 may be returned to its uppermost position by hydraulic means; the springtype accumulator may be replaced by a pneumatic accumulator; the gear motor may be replaced by a blade motor; the monitoring slide valve 4 may be replaced by a rotary device, etc..

What I claim is:

1. A percussion tool actuated by an incompressible fluid which comprises a cylinder, a piston slidably mounted in that cylinder and forming therein an upper chamber and a lower chamber, duct means adapted to cause said incompressible fluid to transmit by successive shocks the energy conveyed by said fluid under pressure to flow into and out of said chambers in order to impart a sustained reciprocating motion to said piston and further comprising an accumulator connected to the oil feed duct from the supply pump to the cylinder, said accumulator being adapted to store the excess fluid output during the upward stroke of the piston and to deliver same during the operative stroke thereof.

2. A tool as set forth in claim 2, which comprises a hydraulic motor, a tool-holding socket rotatably driven from said motor, and duct means connecting said motor to said upper chamber, whereby the oil forced piston blow.

* a :r s 

1. A percussion tool actuated by an incompressible fluid which comprises a cylinder, a piston slidably mounted in that cylinder and forming therein an upper chamber and a lower chamber, duct means adapted to cause said incompressible fluid to transmit by successive shocks the energy conveyed by said fluid under pressure to flow into and out of said chambers in order to impart a sustained reciprocating motion to said piston and further comprising an accumulator connected to the oil feed duct from the supply pump to the cylinder, said accumulator being adapted to store the excess fluid output during the upward stroke of the piston and to deliver same during the operative stroke thereof.
 2. A tool as set forth in claim 2, which comprises a hydraulic motor, a tool-holding socket rotatably driven from said motor, and duct means connecting said motor to said upper chamber, whereby the oil forced out from said upper chamber by the upward stroke of said piston will actuate said motor and thus cause the tool to rOtate by one fraction of a revolution after each piston blow. 